The present invention relates to a mobile telephone system.
With a conventional mobile telephone system which is connected to a public switched telephone network, the signal-to-noise ratio of the signals on a radio channel from a mobile station is constantly monitored by a base station. If it falls below a prescribed level, a line-hold tone is sent to the network. If this condition terminates within a specified period, the line-hold tone is removed to allow both parties to resume the communication. Should it continue beyond the specified period, the connection between the base station and the network is forcibly cleared and an end-of-call signal is sent to the mobile station to clear the radio channel. If this forced disconnection occurs as a result of the mobile station user inadvertently passing beyond the boundary of the system's service area, it is likely that he will recognize the situation, but the network-side user may be left puzzling over the disconnection.
In addition, when there is an incoming call from a network-side user, the base station is alerted by a ringing signal and proceeds to establish a connection between the network and the mobile station. If it fails in this attempt, the call-originating user is left unanswered for an extended period of time.